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Publisher Summary This chapter reviews the anatomic connectivity of the centromedian–parafascicular (CM–Pf) complex, its role in the pathophysiology of movement disorders, and describe the relationship between anatomic stereotactic planning, and surgical and clinical outcome. Macroscopically, the dorsomedial thalamus is surrounded by the lamella medialis on its anterior, lateral, and inferior boundaries. Its length is 18–20 mm according to the distance between the anterior third of the massa intermedia and the habenular commissural plane. The thalamic central gray represents its medial boundary and because of its extension and size, the medial thalamus is commonly known as the nuclear medial region or medial territorium. The CM–Pf complex may play a key role in alleviating L-DOPA-induced involuntary movements. The effect of the DBS of the CM–Pf complex, as well as the effect of selective lesions, might depend on its impact on different neuronal substrates within the CM–Pf complex. The neuronal degeneration in the CM–Pf complex, which commonly occurs in PD patients, may affect preferentially some neuronal subpopulations, and this might modify the effects of the DBS.

Rats with bilateral lesions of either the anterior, central, or posterior dorsomedial thalamus or with sham operations were compared on the acquisition of a food reinforced, tone-light, go/no-go discrimination task in an operant chamber. Rats with small lesions of the central portion of the medial thalamus (centered on the dorsomedial nucleus) were found to be deficient relative to rats with sham or small anterior medial thalamic lesions.